Sean Thomas is a novelist, journalist and travel writer. He also publishes thrillers under the name Tom Knox. He is currently writing a memoir of his extremely misspent youth, and similarly misspent adulthood, and tweets under the name @thomasknox.

If Scotland leaves, we can blame Heath, Letwin, Cameron and Labour

As of this moment, even as I write this blog in rainy London, the threat of Scottish secession looms larger: with some bookmakers, the odds on YES or GOODBYE BRITAIN have just peaked – literally ten minutes ago – at 9/4, almost a 1 in 3 chance; and the latest polls put YES within a three per cent swing of victory.

Three per cent. That’s the swing needed to break up a 300 year-old nation, arguably the most successful and stable in human history. A three per cent swing is required to split Great Britain in two, to make my partly Scottish daughter a foreigner in her own country, to cripple the Labour party, decimate the Lib Dems, shell-shock the Conservative and Unionist party, and send the UK into a constitutional chaos from which it might take decades to emerge.

You can forget your dreams of EU withdrawal and deficit reduction and twice weekly bin collection: they are small beer compared to this. Whatever Alex Salmond says, a Scottish secession will be calamitously complex and difficult, and its consequences will dominate the remaining political lives of many of us: as we try to divide the indivisible, as we struggle to bisect assets shared over centuries, from military bases to fishing grounds, from late colonial possessions to the BBC.

It will be like the world’s worst divorce, multiplied a trillion-fold; it will leave millions of people embittered or angry on either side – denied what they see as their rightful identity. It will be hellish. Yes, better, happier, quieter countries might possibly emerge at the end of it – they will certainly be more Right-wing as they adjust to a cold new reality – but the getting there will be prolonged, and miserable, and tediously, agonisingly fretful.

So how did we reach this stage where we contemplate sawing our country in two? As far as I can see it, there are four guilty parties.

Number 1. Edward Heath, for taking us into Europe. We wouldn’t be here today if we hadn’t joined the European Union. The EU, instead of uniting countries, has proved dangerously fissiparous, as ever smaller regions see a way of asserting identity – while remaining safe within a comfort zone of European quasi-Federalism. Where Scotland is now, Catalonia and the Basque Country are surely following (only with extra guns). After them, who knows: Belgium? Northern Italy?

Number 2. Oliver Letwin. It’s a little known fact that Oliver Letwin, perhaps the most idiotic smart-aleck in all British politics, came up with the concept of the poll tax, and persuaded Margaret Thatcher to adopt it against her better judgement. The poll tax was first imposed on Scotland, and the rest is history, or maybe psychopathology. The Tories never really recovered north of the border, and a disunified UK is the consequence.

Number 3. Just about everyone in the New Labour government. Remember that Scottish Devolution was meant to “kill off Nationalism stone dead”. That’s what Labour said would happen. The trouble is, Labour are a congenitally selfish group of ideological careerists who can never see their country without thinking of a way to put party first, and so Labour refused to give Scotland proper "devo max", i.e. full autonomy, which would have been a durable solution.

Why didn’t they grant devo max? Because devo max would have meant addressing the West Lothian Question – i.e. the continued and anomalous presence of Scots MPs, mainly Labour, voting on English issues at Westminster. And Labour had no intention of removing the unfairness that worked in their favour: they wanted to keep all those lovely Scottish Labour MPs in London, while retaining Scotland as a private fiefdom.

This destabilised everything. It also alienated the English, which further alienated the Scots. A state of affairs which is now leading to the Partition of Britain.

Number 4. David Cameron. Even at the last moment, as he negotiated this referendum, Cameron could have given Scots a devo max option. This would have secured Scotland within the Union – as it was the clear preference of most Scots (according to polls). It would also, by the by, have scuppered Labour down south.

Yet Cameron flunked it. Because he is a fine statesman but a truly terrible politician, with an uncanny instinct for making exactly the wrong choice. His reward, should Scotland vote YES, will be to go down in history as a modern Lord North, the man who lost America. Except Cameron’s epitaph will be worse. The man who lost half his own country.

So there it is. The roll call of indy-shame. If your grand-kids ask you in 50 years, "why on earth is there a great big border down the middle of this beautiful island?" you will be able to give them the names: Heath, Letwin, Cameron, and the entire Labour party 1997-2010. I hope they are heating up the pitchforks in Hell.